Referring to FIG. 1, a known dimensioning system 10 includes a conveyor system 12 that moves items along a path of travel, and a component system 14 adjacent to the conveyor system that tracks packages being moved by the conveyor system. Conveyor system 12 includes a number of rollers 16, a belt 24, a bed 18 and a tachometer 20. It should be understood that the conveyor can move the items through the path of travel by means other than belts, for example by driven rollers. Rollers 16 are motor-driven rollers that move conveyor belt 24 in a direction denoted by arrows 26 over bed 18, which provides support to the belt. For purposes of the present discussion, the direction corresponding to the start of conveyor system 12 is referred to as “upstream,” whereas the direction in which conveyor belt 24 moves is referred to as “downstream.”
Tachometer 20 is beneath and in contact with the surface of conveyor belt 24 and rotates with the belt as the belt moves in the direction of arrows 26. As tachometer 20 rotates, it outputs a signal comprising of a series of pulses corresponding to the conveyor belt's linear movement and speed. Tachometer 20, and other devices that provide signals corresponding to the rate of movement of a conveyor belt, from which the locations of items moving in a path of travel along the belt can be determined, as should be understood by those of ordinary skill in the art. In general, the number of pulses output by tachometer 20 corresponds to the linear distance traveled by the belt, while pulse frequency corresponds to the belt's speed. The number of tachometer pulses per unit of measurement defines the tachometer's resolution and its ability to precisely measure the distance that the conveyor belt has moved. Tachometer 20 may be replaced by a shaft encoder, particularly where less accurate measurements are needed.
Component system 14 includes a dimensioner 28, a plurality of barcode scanners 32, and optionally a separate system computer 36, all of which are attached to a frame 38. Frame 38 supports dimensioner 28 and at least one barcode scanner 32 horizontally above conveyor belt 24 so that beams of light emitted by the dimensioner and scanners intersect the top surfaces of packages moved by the belt. Frame 38 also supports additional scanners 32 vertically adjacent to conveyor belt 24 so that beams of light emitted by these scanners intersect the side, back, front or bottom surfaces of packages moved by the belt. Examples of prior art laser scanner barcode readers include the DS_series, DX8200A, AXIOM and AL5010 barcode readers manufactured by formerly Accu-Sort Systems, Inc. and Datalogic Automation, Inc. of Telford, Pa., although it should be understood that camera-type barcode readers, for example the AV6010 barcode reader manufactured by Datalogic Automation. Inc., or other suitable barcode readers could be used, depending on the needs of a given system.
As should be understood in this art, dimensioner 28 detects one or more dimensions of an item on a conveyor. In a system designed to track singulated packages (i.e. packages carried by the conveyor so that they do not overlap in the direction of travel, and are thus easily distinguishable by a photodetector with a direction of vision in the x direction) the dimensioner is disposed along the conveyor at a known position relative to the bar code readers and a photoeye. When a package moving along the conveyor reaches the photoeye, the photoeye outputs a signal to the dimensioner. The dimensioner also receives tachometer data and therefore knows the tachometer count that occurred when the package was detected at the photoeye. The dimensioner opens a package record and associates the tachometer count corresponding to the photoeye event. The dimensioner also knows the distance (in tachometer pulses) between the photoeye and the dimensioner. Thus, when a package reaches the dimensioner, the dimensioner reads the present tachometer count, subtracts the predetermined distance back to the photoeye, and checks the existing package records for the record having that resulting tachometer count. The dimensioner determines the package's height, width and length, and associates that data in the package record. Alternatively, the photoeye data may be received by separate computer 36, instead of the dimensioner. In such an embodiment, the dimensioner creates an individual package record when a package reaches the dimensioner, determines the package's height, width, and length, associates the dimension data and the tachometer count with the package record, and outputs the dimension data to system computer 36 which, in turn, associates the dimension data with the correct photoeye record.
The barcode reader also receives the photoeye signal and also knows the distance from the photoeye to its scan line. As does the dimensioner, the barcode reader opens a package record upon receiving a photoeye signal indicating presence of a package, and associates the corresponding tachometer value with that record. When a package reaches the reader's scan line, the reader backs the photoeye/reader distance from the present tachometer value, identifies the package record that corresponds to the resulting value, and associates barcode data from the package with the selected record. As should be understood in this art, barcode reader 32 may comprise a laser scanner that projects a plurality of laser lines on the belt, for example in a series of “X” patterns, that the reader utilizes to detect and read barcodes. The barcode processor accumulates barcode data while a given package passes through the X patterns and stores the accumulated barcode data to the package record. More specifically, the barcode scanner processor knows the package length based on the original photoeye data, and so knows, following the point when the leading edge reached the reader's scan line, when the following edge passes. Thus, the reader can store in the record all barcode data detected therebetween.
Each of the dimensioner and the barcode readers know the system transmit point, which is defined in terms of distance, or tachometer pulses, from the photoeye to a point sufficiently downstream of all dimensioners and readers that the trailing edge of the largest package the system is expected to carry will have cleared all tunnel devices by the time the package's leading edge reaches the transmit point. As noted above, all of the dimensioner and the readers track all packages passing the photoeye. Each device accumulates information in a respective package record as the package moves through the tunnel, and each device monitors the tachometer data following creation of each package record. When, following the creation of a package record, the dimensioner and readers determine that a number of tachometer pulses corresponding to the distance between the photoeye and the transmit point have passed, each of these devices outputs its package record to the host system.
As should be understood, however, dimensioners and scan-type barcode readers are utilized in systems other than singulated scanning tunnels. For instance, such devices may be used in non-singulated tunnels, in which packages may overlap in the direction of the belt's travel. Such systems may omit the photoeye, in that packages are not tracked through the system, but on the other hand such systems may utilize sophisticated dimensioning and barcode location algorithms, for example for purposes of determining compliance with size restrictions or identifying items passing through checkpoints. For purposes of the present disclosure, the use of a dimensioner or a scanning type system in other types of devices is not limited to singulated tracking systems and may be used outside of conveyor systems.
The system described with respect to FIG. 1 includes barcode scanners that project an X-pattern across the belt. It should be understood by those skilled in the art that X-pattern scanners can be replaced with line scan readers for detecting and reading barcodes, or with camera-type readers.
Once installed, the dimensioner and readers may be calibrated. One set up and calibration method applicable to such devices is described in U.S. Pat. No. 8,360,318 and Publication 2011/0315770, the entire disclosure of which is incorporated by reference herein. Calibration data may include the dimensioner's and each barcode reader's pitch angle, yaw angle, roll angle, and height with respect to the belt. Particularly where the devices are used in singulated conveyor systems, calibration may also develop a correlation of three dimensional coordinates or other position information among the dimensioner and the readers so that information from the devices can be related among the devices and/or associated with the correct items on the belt.
In the system shown in FIG. 1, dimensioner 28 may be of a type as disclosed in U.S. Pat. Nos. 6,775,012, 6,177,999, 5,969,823, and 5,661,561, the entire disclosures of which are incorporated by reference herein. With regard to such dimensioners, dimensioner 28 comprises a light source, such as a laser, and a rotating reflector disposed within the dimensioner housing that produce a scanning beam (denoted in phantom at 40) that is directed down at conveyor belt 24. That is, the rotating reflector scans the single point light source across the width of belt 24. Each angular position of the reflector represents an x-axis location across the belt. Scanning beam 40 intersects belt 24 at line 42 in a manner that is transverse (x-axis 80) to the belt's linear movement (y-axis 82) in the path of travel at a fixed angle with respect to an axis normal (z-axis 84) to the belt's surface. Packages moving on belt 24, such as package 62, intersect scanning beam 40, thereby creating an offset in the scanning beam in the y-direction (along y-axis 82). In particular, the laser light source is positioned downstream in the y-axis 82 direction so that the plane of light is reflected at an angle from z-axis 84. Thus, as a box moves downstream the intersection of the plane of light is a continuous line across the belt in along x-axis 80. When a box intersects the plane of light, the portion of the plane intersected by the box shifts forward toward the light source (in the y direction) since the light on the box travels a shorter distance than the light that intersects the belt on the left and right sides of the box. This offset or shift in the light on the box surface is proportional to the height of the box.
Both conveyor belt 24 and the packages thereon reflect light created by the scanning beam back to the rotating mirror, which reflects light to a linear array of line scan CCD detectors or a CMOS imager (not shown) within dimensioner 28. The array is oriented parallel to y-axis 82. Because the rotating mirror reflects both the outgoing and reflected laser light, the mirror returns the reflected light to a constant x-axis position, but the reflected light shifts in the y-direction correspondingly to the shift in line 42 caused by the height of a package 62 and the angle at which the scanned laser beam intersects the belt. Thus, the linear array of CCD or CMOS detectors should be accurately aligned in the y-direction to thereby detect the return light's y-axis shift. Moreover, because the array is made up of a single line of pixel sensors, the alignment should be properly aligned to detect the reflected light. The rotating mirror's angular position corresponds to the x-axis position of any given point of reflected light.
In a still further arrangement, a mirrored wheel-type scanning dimensioner may direct a laser scan pattern 40 down to the belt in a vertical plane, parallel to the z axis. As a mirror facet on the wheel sweeps a laser beam across the target surface, that same facet receives the light reflected from the target and reflects this return light back into the dimensioner optics. As long as the beam sweeps across an area of constant height, the return beam reflected from the facet to the detector through the optics remains in a constant position. If the target height changes, however, the return light shifts in the x direction. The amount of the shift depends on the angle between the z axis and the axis of the laser beam (or of the returned light), and there is no shift when the beam is directly vertical. This, in turn, causes a linear shift in the return light on the detector, which can be correlated to height above the belt given knowledge of the wheel's angular position when the shift occurs.
Dimensioner 28 generates a signal representative of the height of an object such as package 62 across conveyor belt 24 as described by the y-axis or, depending on the type of dimensioner, x-axis offset detected in scanning beam 40. The signal is also representative of the x-axis positions of the height data by association of that data with the mirror's angular position. Based on the height data and corresponding x-axis data, the dimensioner processor (not shown) determines the cross sectional height profile of an object on the belt and, by accumulating such profiles along the object's length, the object's three dimensional profile.
Still further, a dimensioner may be configured as described in U.S. Pat. No. 8,360,318, in which a laser projects a light pattern from the dimensioner with an optical axis directed downward in the x-z plane, and at an angle theta with respect to the z axis. As illustrated in and described with respect to FIG. 19 of the '318 patent, a pair of such lasers may be provided, to prevent shadowing, if desired. The laser devices may project a pattern of sequential light and dark bars or dots, or combination of such or other geometric shapes, across the belt in the x direction. The linear sensor is also aligned in the x direction, i.e. transverse to the belt's direction of movement, so that the sensor detects the reflected light pattern. Due to the laser light's projection at angle theta, when an object passes into the laser device(s) field(s) of view, the pattern detected by the sensor shifts in the x direction.
The dimensioner generates a signal representative of the item's height, extending across conveyor belt 24 over the item's width, as described by the x-axis offset detected in the scanning beam. The signal is also representative of the x-axis positions of the height data by identification of the portion of the pattern that shifts, given the otherwise known position of the shifted portion in the overall pattern, as described in U.S. '318. Based on the height data and corresponding x-axis data, the dimensioner processor determines the cross sectional height profile an object on the belt and, by accumulating such profiles along the object's length, the object's three dimensional profile.